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Security marking method and composition

  • US 5,516,362 A
  • Filed: 06/05/1995
  • Issued: 05/14/1996
  • Est. Priority Date: 05/28/1993
  • Status: Expired due to Fees
First Claim
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1. A security marking method comprising the steps of:

  • applying a first marking to a surface of a substrate with a mixture of a printing medium and a first composition, wherein the first marking is visible to an unaided human eye and is indistinguishable from a marking applied with the printing medium alone, to an unaided human eye when illuminated by visible light or ultraviolet light; and

    thereafter activating the first marking upon demand with a second composition, wherein the second composition is reactable with the first composition to fluoresce and wherein the fluorescing is only visible to an unaided human eye when illuminated by ultraviolet light.

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